Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"Nonlinear stability"”.
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Nonlinear stability of multibody systems
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003.
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Distributed nonlinear stability analysis of rotating stall
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1994.
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Finite element nonlinear stability analysis of framed structures
… for the routine analysis of elastic-plastic stability problems in frame structures is addressed. The necessary models, solution procedure and geometric algorithm used for nonlinear stability analysis of frames are presented. An available finite element code, NOSTRUM, which had the basic …
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Combined linear/nonlinear stability analysis of plane and space frames
… is to apply the combined linear buckling and nonlinear analysis to the stability investigations of the plane and space frame structures. A comparative study of the combined analysis and the nonlinear analysis is conducted with ABAQUS to demonstrate the applicability and effectiveness of the …
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Linear and Nonlinear Stability Analyses of Density-Wave Oscillations in Heated Channels
Linear and nonlinear stability analyses of density-wave oscillations in uniformly and non-uniformly heated channels are reported. The two-phase flow is represented by the drift flux model. A constant characteristic velocity v$\sbsp{\rm o}{\*}$ is used to make the set of equations dimensionless to …
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Generalised nonlinear stability of stratified shear flows: adjoint-based optimisation, Koopman modes, and reduced models
… thesis I investigate a number of problems in the nonlinear stability of density stratified plane Couette flow. I begin by describing the history of transient growth phenomena, and in particular the recent application of adjoint based optimisation to find nonlinear optimal perturbations and …
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Nonlinear Stability Analysis of Frame-Type Structures with Random Geometric Imperfections Using a Total-Lagrangian Finite Element Formulation
With the increasing use of lightweight frame-type structures that span long distances, there is a need for a method to determine the probability that a structure having random initial geometric imperfections will become unstable at a load less than a specified fraction of the perfect critical load. …
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A General Framework for the Control of Nonlinear Systems
… effective controller design techniques for nonlinear processes is the lack of a nonconservative framework for analyzing the closed loop stability and performance of generic nonlinear dynamical systems. Such a framework can be developed for systems consisting of interconnections of linear …
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Instability of electrified viscous films
We examine the stability of a thin two-dimensional liquid film with a regular electric field applied in a direction parallel to an initially flat bounding fluid interface. We study the distinct physical effects of surface tension, van der Waals and electrically induced forces for a viscous …
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Generation of discrete frequency tones by the flow around an aerofoil
… of a coupling between laminar boundary-layer instability waves and sound waves propagating in the free stream. The frequency has been predicted by use of various methods based on this model.<br/>In this thesis a review of wind-tunnel results obtained by Dr. E.C. Nash at the University of Bristol …
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Analytical investigations of convective effects on a solid-liquid interface
… with the solid layer thickness. A weakly nonlinear stability analysis reveals that there is subcritical instability irrespective of the interface shape. The stable forms of the solidified front are then found. In the case of hexagonal pattern, the fluid motion is shown to be upward at the …
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Nonlinear control and synchronization of multiple Lagrangian systems with application to tethered formation flight spacecraft
… combinations of biological systems, contraction nonlinear stability theory provides a systematic method to reduce arbitrarily complex systems into simpler elements. One application of oscillation synchronization is a fully decentralized nonlinear control law, which eliminates the need for any …
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Vibration Control for Chatter Suppression with Application to Boring Bars
… qualitative characterization of the chatter instability itself becomes important. Chatter vibrations are finite and recognized as limit cycles, yet modeling and control efforts have routinely focused only on the linearized problem. The question naturally arises as to whether the nonlinear …
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Stability of Periodic Waves in Nonlocal Dispersive Equations
… Dr. Mathew Johnson, we study the existence and stability of periodic waves in equations that possess nonlocal dispersion, i.e. equations in which the dispersion relation between the temporal frequency, omega, and wavenumber, k, of a plane wave is not polynomial in ik. In models that involve only …
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Discrete-time Stable Geometric Controller and Observer Designs for Unmanned Vehicles
… of freedom actuated, in discrete time. Rigorous stability analyses of the tracking control schemes presented here guarantee the nonlinear stability of these schemes. The proposed schemes here are developed in discrete time as it is more convenient for onboard computer implementation and ensures …
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A Theory of Nonlinear Negative Imaginary Systems
… imaginary systems theory to a broad class of nonlinear systems. A formal definition will be given for the negative imaginary property in the nonlinear domain by invoking a new dissipativity notion with an appropriate work rate. This formula is considerably more general than the existing …
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On the dynamics of rigid multi-body systems in orbit
… space systems and gains an insight into the nonlinear dynamics in order to develop efficient control techniques that exploit them. In addition this thesis aims to investigate the usefulness of dynamical systems tools in this area of application. To this end, the dynamics of the free single …
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Contributions to mixing and hypocoercivity in kinetic models
… work contribute to the mathematical study of a stability mechanism common to both the Vlasov–Poisson equation and the Kuramoto equation. These kinetic models come from very different areas of physics: the Vlasov–Poisson equation models plasmas and the Kuramoto equation models synchronisation …
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Flow and stability studies in porous media based on some non-Darcian models.
… thesis deals with the study of certain flow and stability problems in porous media using some non-Darcian models. It is divided into three parts, which are essentially independent of each other. The first part deals with the theoretical study related with the solution of the Brinkman equation. An …
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